explosive gas
detector
CH4 - H2 - C3H8 - CxHy ...
Principles:
CATALYTIC
INFRARED
Connection: 3 wires
Output signal: Wheatstone bridge
ATEX marking: II 2G Ex db IIC T6 - T4
II 2D Ex tb IIIC Tx °C
THE BELGIAN PIONEER IN GAS DETECTION
DALEMANS-FT-detDAX3F_I•LINE_EN
To guarantee safety and performance, all gas detection installations
must be calibrated and maintained regularly in accordance
with the manufacturer’s instructions.
DAX 3F
MEASUREMENT PRINCIPLE
CATALYTIC
The detector sensing element is made
up of two platinum filaments electrically
heated to around 400°C.
One of them (1) is covered with an active
catalytic layer which heats up strongly in
the presence of a combustible gas.
Sensing head
Stainless steel 1,4404 (AISI 316L)
Sintered metal filter
Stainless steel 1,4404 (AISI 316L)
Junction box Aluminium
Dimensions (LxWxH) / Weight
170 x 145 x 90 mm / 1400 g
Output signal
3-wire mV (Wheatstone bridge)
Response time (T90) < 30 s
Type
DAX 3F-CA
DAX 3F-IR
Measuring principles
Catalytic
Infrared
Supply voltage * 1,925 - 2,025 V
3,2 - 5,0 V
Consumption * 155 - 195 mA
75 - 85 mA
Operating temperature -20 °C to +55 °C (T6 t° class)
-20 °C to +50 °C
Storage temperature
-40 °C to +80 °C
-20 °C to +50 °C
Ambient humidity
20 - 90 % RH
0 - 95 % RH
± 3 % full scale < 60 % LEL ± 0,5 % full scale < 50 % LEL
Accuracy
± 5 % full scale > 60 % LEL ± 1 % full scale > 50 % LEL
Lifetime
> 2 years
> 5 years
Cable cross section
1,5 - 2,5 mm2 (solid wires)
Cable entry
1 x M20 / 6,1 - 11,7 mm (other sizes available)
Refer to the installation instructions
Max. cable length
of the control unit
Hazardous areas
Zone 1 or 2 (gas). Zone 21 or 22 (dust)
Casing ingress protection
IP66
Equipment gas grouping IIC (methane, propane, ethylene, hydrogen, acetylene)
Equipment dust grouping
IIIC (conductive dust)
Standards
EN 60079-0 • EN 60079-1 • EN 60079-31
Approval (ATEX + IECEx)
II 2G Ex db IIC T6 - T4 •
II 2D Ex tb IIIC Tx °C
Certificates
FTZU 09 ATEX 0313X
* Depends on type of cell used.
GASES CONCERNED
Measurement
Density range
L.E.L.
Gas
Formula (air=1) (% L.E.L.) (% vol.) DAX 3F-CA
0,90
0 – 100 2,30
Acetylene
(CH)2
•
2,05
0 – 100 1,40
Butane
C4H10
•
0 – 100 3,10
Ethylene oxide C2H6O 1,59
•
Natural gas
-
0,68
0 – 100
-
•
Hydrogen
H2
0,07
0 – 100 4,00
•
Isobutane
(CH3)3CH 2,00 0 – 100 1,30
•
Methane
CH4
0,55
0 – 100 4,40
•
Propane
C3H8
1,56
0 – 100 1,70
•
DAX 3F-IR
•
•
•
This temperature increase causes an
increase in the resistance of the filament which is measured in the unit.
The other filament (2), passive, serves as a
thermal compensator.
1
2
GAS
INFRARED
The infrared cell functions according to the
non-dispersive infrared (NDIR) principle. It
is made up of a casing comprising:
- a diffusion membrane (1),
- a measurement chamber (2),
- an IR radiation source (3),
- an active sensor (4) and
- a reference sensor (4’).
The gas that reaches the measurement
chamber absorbs - within a very precise
range of wavelengths - a part of the
radiation emitted by the IR source.
The active sensor measures the remaining
IR radiation and thereby determines the
concentration of the gas present. The
reference sensor measures the IR radiation
within a range of wavelengths that is not
influenced by the incoming gas. Its signal
serves to compensate any variation in IR
radiation which is not due to absorption
caused by the targeted gas, such as a variation in temperature, humidity level, etc.
This enables us to obtain an accurate
and reliable measurement in all conditions.
3
2
•
•
Other gases upon request.
4
4’
1
GAS
rue Jules Mélotte 27 - B-4350 Remicourt
Tel.: +32 (0)19 33 99 43 • Fax: +32 (0)19 33 99 44 • [email protected] www.dalemans.com
The information contained in this documentation is non-contractual and subject to modifications.
CHARACTERISTICS